COPEGUS
Clinical safety rating: caution
Comprehensive clinical and safety monograph for COPEGUS (COPEGUS).
Ribavirin is a nucleoside analogue that inhibits viral RNA synthesis by interfering with RNA capping and polymerase activity, and may also modulate immune responses.
| Metabolism | Metabolized via reversible phosphorylation and deribosylation; approximately 40% of an oral dose is excreted unchanged in feces. Phosphorylated forms accumulate in erythrocytes. |
| Excretion | Ribavirin is primarily eliminated renally as unchanged drug (61%) and metabolites (30%); biliary/fecal excretion accounts for ~9%. |
| Half-life | Terminal elimination half-life is approximately 120-170 hours following multiple doses, supporting once-daily dosing with prolonged viral suppression. |
| Protein binding | Ribavirin is approximately 0% bound to plasma proteins. |
| Volume of Distribution | Volume of distribution is approximately 200-300 L (2.9-4.3 L/kg), indicating extensive tissue distribution. |
| Bioavailability | Oral bioavailability averages 64% (range 36-76%) due to first-pass metabolism, with food increasing absorption. |
| Onset of Action | Oral administration: declines in serum HCV RNA detectable within 2-4 weeks of initiating combination therapy with interferon alfa-2a. |
| Duration of Action | Clinical effect duration aligns with treatment course (24-48 weeks via pharmacokinetic-pharmacodynamic modeling); steady-state achieved in ~4 weeks, and viral suppression persists through dosing interval. |
800 mg orally twice daily to 1200 mg orally twice daily based on body weight (≤75 kg: 800 mg; >75 kg: 1200 mg), in combination with ribavirin, for 24 to 48 weeks depending on genotype.
| Dosage form | TABLET |
| Renal impairment | Contraindicated if CrCl < 50 mL/min. For CrCl 30-50 mL/min: reduce to 400 mg orally twice daily; not recommended if CrCl < 30 mL/min. |
| Liver impairment | Contraindicated in decompensated cirrhosis (Child-Pugh class B or C). No specific dose adjustment for Child-Pugh class A; use with caution and monitor. |
| Pediatric use | Weight-based: <47 kg: 45 mg/kg/day (max 2400 mg) in two divided doses; ≥47 kg: 1200 mg orally twice daily. Duration determined by genotype and response. |
| Geriatric use | No specific dose adjustment based on age alone; monitor renal function and reduce dose if CrCl < 50 mL/min; use with caution due to increased risk of anemia and other adverse effects. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for COPEGUS (COPEGUS).
| Breastfeeding | Unknown if ribavirin is excreted in human breast milk. Due to potential for serious adverse effects in nursing infants (similar to teratogenic potential), breastfeeding is contraindicated during therapy and for 6 months after last dose. No M/P ratio available. |
| Teratogenic Risk | FDA Pregnancy Category X. Ribavirin, the active component, is contraindicated in pregnant women and partners of male patients due to demonstrated teratogenicity and embryolethality in all animal species tested. Risk of fetal harm (including CNS, skeletal, and eye malformations) if exposure occurs during first trimester. Use during second or third trimester also carries risk; pregnancy must be excluded before initiation and avoided during treatment and for 6 months after completion in both female patients and female partners of male patients. |
■ FDA Black Box Warning
Ribavirin monotherapy is not effective for chronic HCV infection. Hemolytic anemia (worsening of cardiac disease). Teratogenicity and embryolethality.
| Serious Effects |
Hypersensitivity to ribavirin, pregnancy or partners of pregnant women, hemoglobinopathies (e.g., thalassemia major, sickle cell anemia), autoimmune hepatitis, CrCl <50 mL/min.
| Precautions | Hemolytic anemia (monitor hemoglobin), cardiac disease exacerbation, pulmonary insufficiency, pancreatitis, hepatic decompensation, myelosuppression, fetal harm. |
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| Fetal Monitoring | Monthly pregnancy testing during treatment and for 6 months after discontinuation in all women of childbearing potential. In male patients, monitor partner's pregnancy status. Fetal ultrasound if unintended pregnancy occurs. Monitor maternal CBC, LFTs, and thyroid function monthly due to combination therapy with interferon alfa. |
| Fertility Effects | Reversible oligospermia and reduced sperm motility reported in male patients receiving ribavirin-containing regimens. Women may experience temporary menstrual irregularities. No permanent effect on fertility documented; contraception required during and for 6 months post-treatment for both sexes. |